m4 selector problems
 

my m4a1 selector switch works fine on safe and semi, but on full auto it locks the trigger as if it's still on safe. sometimes if i bang on the side of the gun a bunch it'll let me use auto but usually not for long. i've taken apart the gun completely a few times to look for anything out of wack but i can't find anything. does anybody have any suggestions?

I had the same problem before and it was created by a bad fitting of my CA metal body with my TM gearbox so it could be the same thing for you.

were you able to fix the problem by sanding the inside of the body down?

is it the trigger or the selector switch that doesnt lock on full auto? examine you selector lever and or check the little spring on the selector plate is it is still there.

spring on the selector plate is still there. the selector plate and switch move as intended but when you put the selector switch on full auto, you can't pull the trigger; it's as if the selector is on safe but it's not

When you reassemble it, do you place the selector on semi when installing the lower receiver?

yeah

Got me thinking right now. I have a ripped apart G&P mechbox on my bench right now, will get back to it and think about your problem while working on it.

How many times has the mechbox on yours been taken apart? Might help to answer the question if we knew. If never, stock gun, then it confuses me more.

I have the exact same problem actually. CA body with a TM mechbox. Fires full auto fine when the selector switch is removed and the plate pushed into position manually. How did you fix this?

the gearbox has probably been opened more times than it's been fired haha! i bought this gun used and it seems to be a mutt when it comes to parts, but i'm pretty sure i have an early generation CA metal body because of the colt trademarks (as opposed to the newer armalite trades) and a CA marking on the right side of the receiver. i'm not sure of the make of the gearbox but it very well could be TM (the motor plate at the bottom of the pistol grip is marked TM and it came with a EG1000 so i wouldn't be surprised). strange thing is auto used to work but now it doesn't. there's gotta be a way to fix it so it works all the time...

hey Ricoius/Brakoo, what markings do your CA bodies have over the magwell? colt, classic army, or armalite?

There was a great fix for this problem and I've done something a little more mickey mouse than it. It has to do with the "rocker" that the selector plate moves and it's inability to move back all the way so it's caught in between semi and full auto. THe fix mentioned before involved a spot of JB weld in the selector plate which pushes the "rocker" back further than the selector plate can. In other words, CA metal bodies with TM mechboxes = lots of headaches. I used a little electrical tape on the "rocker" (need to find the correct term for it) and it works like a charm.

so, to clarify, you put eletrical tape on the semi-oval metal disk thingy? did you put the tape on top of it or between the disk and the metal body?

I wouldn't recommend my mickey mouse workaround... I am only trying to help you come up with a more permanent solution. But I'll try to find that picutre of where it goes. I rolled a little piece of electrical tape in between the "rocker" and the selector plate. The "rocker" is the matel piece that is "attached" to the selector plate via the spring. If you lay the mechbox flat on it's side you'll see a little metal piece sticking out of mechbox attached to the spring. Thats the "rocker" I call it. By putting the tape there I can get it to fire perfectly but I can't guarantee it staying there for a long time. A spot of JB weld in that position supposedly works better.

ahhhhhh the little metal lever that the nub on the bottom of the sector gear hits right?

Yup, that'd be the one.